CVE-2026-9546
Fixed in a distro release EPSS <1%CVSS 7.5
A vulnerability in libcurl caused the HTTP `Referer:` header to persist even when explicitly cleared. While the documentation states that passing NULL to `CURLOPT_REFERER` suppresses the header, the option failed to clear the internal state. As a result, the previous referrer string was erroneously reused and sent in subsequent requests, potentially leaking sensitive information to unintended servers.
Products: curl
Distro releases
| Release | Package | Fixed in |
|---|---|---|
| Alpine 3.23 | curl | 8.22.0-r0 |
| Alpine 3.24 | curl | 8.21.0-r0 |
| Chainguard | eco-python-curl | 8.21.0-r0 |
| Chainguard | eco-python-curl-minimal | 8.21.0-r0 |
| Chainguard | eco-python-curl-minimal-bin | 8.21.0-r0 |
| Chainguard | eco-python-curl-minimal-dev | 8.21.0-r0 |
| Chainguard | eco-python-curl-minimal-doc | 8.21.0-r0 |
| Chainguard | eco-python-curl-minimal-static | 8.21.0-r0 |
| Chainguard | eco-python-curl-nghttp2 | 8.21.0-r0 |
| Chainguard | eco-python-curl-nghttp2-bin | 8.21.0-r0 |
| Chainguard | eco-python-curl-nghttp2-dev | 8.21.0-r0 |
| Chainguard | eco-python-curl-nghttp2-static | 8.21.0-r0 |
| Debian 14 | curl | 8.21.0~rc2-1 |
| Red Hat hummingbird 1 | cargo | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | clippy | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | curl | 0:8.21.0-0.1.hum1 |
| Red Hat hummingbird 1 | libcurl | 0:8.21.0-0.1.hum1 |
| Red Hat hummingbird 1 | libcurl-devel | 0:8.21.0-0.1.hum1 |
| Red Hat hummingbird 1 | libcurl-minimal | 0:8.21.0-0.1.hum1 |
| Red Hat hummingbird 1 | rust | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-analyzer | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-debugger-common | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-doc | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-gdb | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-lldb | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-src | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-std-static | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-std-static-aarch64-unknown-none-softfloat | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-std-static-aarch64-unknown-uefi | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-std-static-i686-pc-windows-gnu | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-std-static-wasm32-unknown-unknown | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-std-static-wasm32-wasip1 | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-std-static-x86_64-pc-windows-gnu | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-std-static-x86_64-unknown-none | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rust-std-static-x86_64-unknown-uefi | 0:1.96.1-1.hum1 |
| Red Hat hummingbird 1 | rustfmt | 0:1.96.1-1.hum1 |
| Ubuntu 26.04 LTS | curl | no fix |
| openSUSE Tumbleweed | curl | 8.21.0-1.1 |